This invention relates to an improvement on a spreader for field application of particulate fertilizers and/or pesticides. More particularly, this invention is directed to an improved hopper and feed wheel assembly which provides for uniform discharge of fertilizer or pesticide with minimal concomittant crushing or caking of the fertilizer or pesticide when said hopper is employed in a conventional spreader.
Fertilizer and/or pesticide spreaders currently employed in orthodox agricultural practice are typically equipped with one or more hoppers or bins for storage and metered discharge of the fertilizer or pesticide during field use. As a rule, these hopper or storage bins are box like containers having bottom outlets for continuous discharge of fertilizer into a series of tubes or channels leading to equally spaced diffusers or other suitable dispensing means at ground level for application of the fertilizer or pesticide to the soil. To control the rate at which the fertilizer or pesticide is released, the size of the bottom outlet from the hopper is typically adjustable in accordance with calibrated settings and the hopper is further equipped with some sort of scraping device located near the bottom discharge e.g., fluted feed wheel or shaft, to promote continuous discharge of fertilizer or pesticide in accordance with the rate at which the spreader moves across the field. Conventionally, this scraping device is a rotatable shaft equipped with scraper blades or flutes which is geared in some manner to the axle of the spreader so that it is powered by, and rotates with, movement of the spreader. For example, the "7100 Mounted Max-Emerge Planter" Series planter/spreaders sold by John Deere employ insecticide and/or herbicide hoppers which are opened top (coverable by a hinged lid) box-like containers with concave bases having bottom slit-shaped discharge openings which may be adjusted in size or closed by means of a movable metal plate. The insecticide and/or herbicide hopper of this series planter/spreader is also equipped with a fluted feed wheel, that is a rotatable metal shaft having radially extending blades or cleats, located immediately above the slit shaped discharge opening which is rotated by means of a chain drive geared from the axle shafts of the spreader wheels. While this spreader and others like it having blade-type feed wheels for uniform discharge of granular product from the hopper operate in a satisfactory fashion in many field applications, certain problems have been experienced with continued or long term use. Specifically, it has been found that some pesticide products exhibit a tendency to pulverize and cake around and immediately below the hopper outlet. Further, the radially disposed blades or cleats on the feed wheels show considerable wear, becoming torn and jagged after extended use. While the cause of these problems has not been established with certainty, it appears that the churning action of the cleats acts to crush and pulverize the pesticide granules, causing the pesticide to become compacted rather than flowable in the area of the hopper outlet. This compacted medium promotes abrasion of the cleats causing the excessive wear observed.
From the foregoing, it is apparent that considerable advantage would be obtained if the hopper/feed wheel assembly could be modified in some way to avoid the problems associated with fluted or cleat-type feed wheels.